import java.util.Scanner;
public class Main{

    public static void main(String []args){
        Scanner in = new Scanner(System.in);
        int num = in.nextInt();
        int count = 0;
        int x = num;

        String temp = Integer.toString(num);
        for(int i = 0;i<temp.length();i++){
            if (x % 10 == 2) {
                count++;

            }
            x = x / 10;
        }

        int len = temp.length();
        double [] list = new double[len];
        double y = Math.floor(num / (Math.pow(10,(len-1))));
        list[len-1] = y;
        double answer = 0;

        while(len >= 1){
            if(y > 2) {
                answer += (1 * Math.pow(10, len - 1));
            }
            if(y >= 2 || list[len-1] != 2 ) {
                answer += ((y) * ((len - 1) * (Math.pow(10, len - 2))));
            }
            if(list[len-1] == 2){
                answer += num % Math.pow(10,len-1);
            }
            len --;
            y = Math.floor((num / (Math.pow(10,(len-1))) % 10));
            if(len != 0) {
                list[len - 1] = y;
            }
        }

        answer += count;
        System.out.println(answer);
    }
}